Infiltrate DOES NOT let you drop the infantry on a hex you do not have vision of.
Airborne DOES let you drop the infantry on a hex you do not have vision of.
Honestly I never felt like you should have to have vision of a hex to drop a unit there. If it is occupied the player gets a message saying that the hex is occupied and the card is cancelled. It's a risk dropping when you don't have vision because your card might not work.
I'd prefer if units could be dropped without vision, but if you guys decide that isn't what is best let us know why and also make all cards (including heroes, airlift, etc) follow the same rule